1. Field of the Invention
The present invention relates generally to walls constructed of blocks and, more particularly, to double-wall structures of dry-stacked blocks.
2. Background Information
Walls are used in various construction projects and are available in a wide variety of styles. Numerous methods and materials exist for the construction of walls. Such methods include the use of natural stone, poured concrete, precast panels, masonry, and landscape timbers or railroad ties.
Two known types of common walls are fence walls and parapet walls. Fence walls are typically used as landscape structures for soil retention and for protection of natural and artificial structures. Parapet walls are wall-like barriers at the edge of a roof, terrace, balcony or other structure. For roof, terrace and balcony applications, parapet walls are in the form of low walls that also function as a replacement for hand rails and are provided for various reasons, including safety and aesthetics. In another particular application, parapet walls are used as reinforcement against the accidental impact of vehicular traffic.
In recent years, concrete wall blocks, which are dry stacked (i.e., stacked without the use of mortar), have become widely accepted in the construction of walls. Such wall blocks have gained popularity because they are mass produced and, consequently, relatively inexpensive. They are structurally sound, easy and relatively inexpensive to install, and couple the durability of concrete with the attractiveness of various architectural finishes.
The current use of such wall blocks to build fence and parapet walls has been limited to the use of columns or piers as a method of reinforcing the fence or parapet wall. These columns or piers are routinely placed atop and anchored to a poured, steel-reinforced, concrete foundation that requires a different labor force for construction than the one used to install the wall. The actual fence itself may require a concrete foundation. In the case of fence wall applications, the columns or piers are regularly spaced and used as reinforcement against wind-loading. In the case of parapet wall applications, the columns or piers are placed atop a retaining wall, such as adjacent a parking lot, for use as reinforcement against accidental impact of vehicular traffic.
The conventional structures and methods for constructing fence walls and parapet walls utilizing segmental concrete wall blocks have suffered from various drawbacks, including difficulty in installation and high construction costs. In the case of fence walls, the conventional methods and structures have been unable to achieve sufficient resistance to wind-loading forces. In the case of parapet walls, the conventional methods and structures have been unable to provide an adequate retaining function as a handrail or to resist the forces of accidental vehicular traffic impact.